A cosmic double take

The image on the left is a view of the entire sky with the light from stars, galaxies, dust and gas subtracted. What remains is the cosmic microwave background, a type of relic radiation from the early universe that can be detected long after it was first emitted billions of years ago. The view comes from NASA’s WMAP probe launched in 2001. The colours represent slight variations in temperature and their precise pattern reveal details about the origin and contents of the universe.

On the right is the latest view of the cosmic microwave background, provided by the European Space Agency’s Planck mission. As it is many times sharper, it allows researchers to disregard some ideas about how the universe formed in favour of others. The new data reveal that the universe is 13.8 billion years old, or about 100 million years older than previously thought. Further analyses may reveal more about the Big Bang, the event that triggered the birth of the universe, and whether there are other universes besides our own.